Circulating serogroups of Leptospira in swine from a 7-year study in France (2011–2017)

Abstract

AbstractBackgroundLeptospirosis is a widespread zoonotic disease caused by pathogenicLeptospiraand is responsible for significant economic porcine livestock losses. Knowledge ofLeptospiraserogroups and their distributions is important for evaluation of the relevance of leptospirosis management measures, including use of the prophylactic vaccine that was recently made available in France. A retrospective study was conducted to determine the relationships between different circulatingLeptospiraserogroups. Pigs from across France presenting clinical signs suggestive of leptospirosis were tested with the microagglutination test (MAT) between 2011 and 2017. We used weighted averages to determine serogroup distributions according to MAT results and considering cross-reactions.ResultsA total of 19,395 pig sera, mostly from Brittany, were tested, and 22.7% were found to be positive for at least oneLeptospiraserogroup. Analysis of the 4,346 seropositive results for which the putative infective serogroup could be defined, revealed that two out of ten serogroups were much more frequent than the others: Australis (48.5%) and Icterohaemorrhagiae (38.2%). Other serogroups, including Autumnalis, Panama, Ballum, Tarassovi, Sejroe, Grippotyphosa, Bataviae, and Pomona, were less common.ConclusionsAlthough diagnostic laboratory data cannot be extrapolated to infer the distribution ofLeptospiraserogroups at the nationwide scale in France, the analysis of such data can provide an overview of the relationship between circulatingLeptospiraserogroups in space and time. During the last decade, protection against the serogroups Australis and Icterohaemorrhagiae would have prevented most of the clinical porcine leptospirosis cases in the large number of farms that we studied. In the future, epidemiological information related to circulatingLeptospiraserogroups should be extracted from data with a standardized approach for use in nationwide or international surveillance and prophylactic strategy support.